3b vascular system Flashcards
What is the vascular system?
The network of blood vessels in the human body that transports blood throughout the body.
What is the function of arterioles?
They are high-resistance vessels that regulate blood flow into capillaries.
What happens at the capillaries?
Exchange of nutrients and waste between blood and tissues.
What vessels return blood to the heart?
Venules → Veins → Venae cavae or pulmonary veins.
What are the three layers of most blood vessels (excluding capillaries)?
Tunica intima, tunica media, tunica adventitia.
What is the function of the tunica intima?
Acts as a barrier and secretes vasoactive products.
What is the function of the tunica media?
Provides strength, elasticity, and contractile power.
What is the role of the tunica adventitia?
Connective tissue that anchors vessels and contains vasa vasorum in large vessels.
What are elastic arteries?
Large, elastic-rich arteries that help maintain blood flow during diastole (e.g., aorta, pulmonary artery).
What are muscular (conduit) arteries?
Medium-sized arteries with thick smooth muscle layers that resist collapse and regulate blood flow (e.g., radial, cerebral arteries).
Why are arterioles called resistance vessels?
Due to their narrow lumen and ability to regulate flow with smooth muscle contraction.
What is special about capillaries?
They have a single endothelial layer and are the primary site of exchange.
What is an arteriovenous anastomosis?
A vessel that bypasses capillary beds, aiding in temperature regulation (e.g., in skin, nasal mucosa).
Why are veins called capacitance vessels?
They store most of the body’s blood and can mobilise it during stress.
What prevents backflow in veins?
Valves, especially in limbs and below the heart.
features of arteries
arteries
1. away from heart
2. rounded
3. high pressure
4. thick walls
5. high o2 conc
6. no valves
features of veins
veins
1. towards heart
2. irregular appearance, often collapsed
3. low pressure
4. thin walls
5. low o2 conc, except pulmonary
6. valves
What are the 4 parts of the aorta?
Ascending, Arch, Descending (Thoracic), Abdominal.
What arteries branch from the aortic arch?
Brachiocephalic trunk (→ right subclavian + right common carotid), left common carotid, left subclavian.
What does the common carotid artery split into?
Internal (brain) and external (face/scalp/neck) carotid arteries.
What does the subclavian artery become in the arm?
Axillary → Brachial → Radial & Ulnar arteries.
What are the 4 major abdominal aorta branches and their targets?
Coeliac trunk (T12): Foregut organs
Superior mesenteric (L1): Midgut
Renal arteries (L1–L2): Kidneys
Inferior mesenteric (L3): Hindgut
What happens at L4 in the aorta?
It bifurcates into the right and left common iliac arteries.
What veins form the superior vena cava?
Internal jugular + subclavian veins → Brachiocephalic veins → SVC
